US6211525B1 - Detector devices - Google Patents

Detector devices Download PDF

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US6211525B1
US6211525B1 US09/214,007 US21400798A US6211525B1 US 6211525 B1 US6211525 B1 US 6211525B1 US 21400798 A US21400798 A US 21400798A US 6211525 B1 US6211525 B1 US 6211525B1
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light
guide
electrons
electron
specimen
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Michael John Cowham
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K E DEVELOPMENTS Ltd
KE Devs Ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
    • H01J37/02—Details
    • H01J37/244—Detectors; Associated components or circuits therefor
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2237/00—Discharge tubes exposing object to beam, e.g. for analysis treatment, etching, imaging
    • H01J2237/244—Detection characterized by the detecting means
    • H01J2237/2443—Scintillation detectors
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2237/00—Discharge tubes exposing object to beam, e.g. for analysis treatment, etching, imaging
    • H01J2237/244—Detection characterized by the detecting means
    • H01J2237/2445—Photon detectors for X-rays, light, e.g. photomultipliers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2237/00—Discharge tubes exposing object to beam, e.g. for analysis treatment, etching, imaging
    • H01J2237/248—Components associated with the control of the tube
    • H01J2237/2482—Optical means

Definitions

  • This invention relates to detector devices, and concerns more particularly devices for detecting electrons emanating from the specimen being examined by a scanning electron microscope or the like.
  • the specimen to be examined is illuminated with visible light—that is, photons with wavelengths in the range to which the human eye is sensitive—and then viewed either by gathering and using the reflected light, to provide information about its surface and shape, in the way that any ordinary object is viewed by the eye, or by gathering and using the light that has been transmitted through it, to disclose details of its internal construction.
  • Magnifying lenses and mirrors can be employed to increase the size of the image, and so make the specimen seem larger, and thus reveal features that the unaided eye cannot see, but inevitably there comes a point—at about 2000 times magnification—where further magnification is impossible because the items to be seen are much the same size as, or even smaller than, the wavelength of the light being used (and so in effect the light travels round them rather than impinging upon them, and without any interaction is unable to reveal anything about them).
  • the “average” wavelength of visible light is around 600 nanometer (0.6 micrometer); by way of illustration, a light microscope can be employed to examine a bacterium or bacillus, because these are relatively large (about 10 micrometer and more in length), but it cannot be utilised to provide clear pictures of viruses, which, at a mere 1 micrometer or less across, are too small to be seen in any fine detail using light.
  • Electrons can behave as a waveform, much like the photons of light, but with a very much shorter wavelength (commonly around 0.001 micrometer and below); they can, therefore, be used to “look at” objects, such as viruses, and details of objects, that are much too small to be seen clearly with a conventional light microscope.
  • TEM Transmission Electron Microscope
  • SEM Scanning Electron Microscope
  • the beam of electrons impinging upon the target—the specimen—in an SEM can give rise to several different varieties of emanating electron. Most obviously there are those electrons that are transmitted through the specimen and are “viewed” from the reverse side; in this mode the microscope is acting as a Scanning Transmission Electron Microscope, or STEM. Next, there are the electrons from the beam that get reflected, or “back-scattered”, off the specimen's surface; the invention is mainly concerned with these. Finally, there are the electrons that originate in the atoms from which the specimen is made, and which have been knocked free from those atoms by collisions with the scanning beam electrons; the freeing of these electrons is known as “secondary electron emission”.
  • the electron beam can also cause other useful, and usable, energy forms to be emitted by the specimen.
  • some specimens will be of a material that, when struck by electrons, gives out electromagnetic radiation; depending on the material this radiation might take the form of X-rays or it might manifest itself as visible light photons.
  • the emission of such photons is known as Cathodoluminescence Emission (CE).
  • the SEM In order to benefit from the effects of the electron beam the SEM must have some way of gathering the emanating electrons and converting them into a visible image. Moreover, because the intensity of the gathered electrons is inevitably rather low—in simple terms the specimen does not seem very bright—it is common directly or indirectly to amplify either the electrons themselves or the image they form until it is convenient for the human eye to see.
  • One conventional method of achieving this is to cause the electrons to strike a scintillator—a device (or material) that gives off flashes of light when hit by electrons—and then to direct the thus-formed light to a photomultiplier which converts the flashes into significantly large pulses of electricity (“back”, as it were, into electrons, but now in such large quantities that they can be used to drive or control ordinary equipment such as television or cathode ray screens). It is this, the primary detection of the gathered electrons (and specifically the back-scattered electrons) by their conversion into light using a scintillator, and the feeding of the thus-formed light to a photomultiplier tube or the like, with which the invention is primarily concerned.
  • a scintillator a device (or material) that gives off flashes of light when hit by electrons—and then to direct the thus-formed light to a photomultiplier which converts the flashes into significantly large pulses of electricity (“back”, as it were, into electrons, but
  • a solid finger-like light guide usually of a transparent acrylic plastic, though glass or quartz can also be employed
  • a layer of scintillator material typically a phosphor
  • the finger is mounted by its other end adjacent and projecting from the input screen of a photomultiplier tube (PMT), or the like, orientated with the scintillator layer facing the specimen, and poked into the path of the back-scattered electrons such that they impinge upon the layer to cause it to emit light. This light then passes through the layer into the body of the finger, which guides it (by total internal reflection) along to the far end where it shines out into the PMT.
  • PMT photomultiplier tube
  • This type of detector system which has been in use for several years, is quite good, but nevertheless suffers from a number of disadvantages, of which perhaps the most serious arises from the conflicting requirements for the scintillator layer.
  • the problem is that the layer needs to be thick, and relatively opaque to electrons, so as to have the best chance of capturing, and thus making light pulses from, most of the electrons that hit it (rather than letting them wastefully pass through without generating light), and yet at the same time it is most preferably thin enough to let those very pulses of light pass though it into the body of the light guide finger rather than being absorbed in and attenuated by the layer and so squandered.
  • an improved version of the light-directing finger having, instead of the side surface layer of scintillator material at the end to be inserted into the stream of back-scattered electrons, an electron receptor disposed so as to have a face angled as though to reflect received electrons along the finger to the PMT and having the scintillator material coating on that face.
  • the PMT is actually “looking at”, and so receiving light directly from, the front, or input side, of the scintillator layer, rather than, as in the Prior Art detector described above, effectively looking at the back, or output side of the layer.
  • the light that is emitted by the layer does not need to travel through the layer to get to the PMT, and is therefore not attenuated by that layer—and a detector system of the invention is therefore several, even tens, of times more sensitive that one of the Prior Art.
  • this invention provides an electron-gathering light guide for attachment to a light magnifier, the guide comprising
  • an elongate light-guiding body mountable at one end at the magnifier, there being at the other end—the end to be inserted in use into the stream of electrons emanating from the specimen
  • an area-extensive electron receptor disposed so as to have a face angled as though to reflect received electrons along the body to the mounting end, and having on that face a scintillator layer at which, in operation, received electrons are converted to photons which are then radiated away from the input surface of the layer towards the light magnifier.
  • the electron-gathering light guide of the invention is for use with an electron microscope, particularly a scanning electron microscope (SEM). It is not necessary at this juncture to discuss the details of SEMs, though it is perhaps convenient to note that the basic components of such a device are shown in one of the Figures of the accompanying Drawings. It is also worth observing that the narrow beam of electrons the SEM produces is generated by an electron gun at a high negative potential, frequently around 20,000 Volts (20 kV), but that the operation of most SEMs is in fact possible between 1 kV and 30 kV (and indeed some SEMs operate over an even wider range of voltages).
  • SEM scanning electron microscope
  • the electron-gathering light guide of the invention is for attachment to a light magnifier.
  • the means of attachment can be any that is appropriate to the particular magnifier utilised—it might be a screw-threaded coupling ring or a bayonet fitting—while the magnifier itself may be any suitable light magnifying device, such as a photomultiplier tube (PMT).
  • PMT photomultiplier tube
  • a typical photomultiplier tube is that bialkali type R268 tube sold by Hamamatsu, of Japan.
  • the invention's electron-gathering light guide comprises an elongate light-guiding body mountable at one end at the light magnifier and having at the other end an electron receptor.
  • This body may take a number of forms, including that of a solid transparent “pipe” much like that used in the Art, but the preferred one is that of an internally-reflective (hollow) tube.
  • a tube can be of any appropriate cross-section, and may be constructed in any suitable way.
  • a preferred tube is of rectangular section and of a wedge shape (tapering down towards the receptor end, so as to fit within the confined space above the specimen), and is fabricated from four separate elongate planar metal plates each made reflective on its “inner” surface.
  • the plates which should be of a non-magnetic but conductive material, typically aluminium, can be highly polished to provide the reflective surfaces, or they can be given a reflective coating (which may be appropriate to the nature of the light emitted by the scintillator; thus, gold coatings are preferred for infrared).
  • the preferred form for the elongate light-guiding body is that of an internally-reflective tube mountable at one end at the light magnifier and having at the other end an electron receptor.
  • This tube is most preferably wedge-shaped, tapering down from the magnifier end, where it is sized to fit over the input face of the magnifier, towards the tip, or receptor end, where it is sized—and more specifically made wide but thin—to fit within the confined space between the specimen and the output of the SEM.
  • the tip should be as thin as possible so as to fit within the available space while it should also be as thick as possible for the most efficient gathering and transmission of the small light signals emitted by the scintillator.
  • the tip has a thickness of around 4 mm.
  • the body of the electron-gathering light guide is mountable at one end at the light magnifier and has at the other end an electron receptor.
  • the receptor is an area-extensive device—that is, it extends to cover, and thus gather emanated electrons over, a significant area (defining a suitably large solid angle subtended from the specimen)—and is so disposed that what might be termed its “working” face—that face of it that receives electrons emanating from the specimen—is angled as though to reflect the received electrons along the guide body to the mounting end. On that face is a scintillator layer.
  • the receptor is merely a rigid supporting substrate—a plate, or plate-like member—with the scintillator layer on its working face, and is mounted at the end of the body (in any suitable way, but preferably detachably so that it may more easily be changed or replaced) with the face angled to look both at the specimen and (along the body) at the magnifier.
  • the receptor substrate is a thin wedge, the wedge surface carrying the scintillator layer and angled to face both the specimen and the magnifier.
  • the face's angle is merely any angle which will allow the face to receive directly electrons from the specimen and also will permit the light that the scintillator layer's surface emits to shine directly into the guide without first passing through any of the thickness of the layer.
  • Angles of from around 20° to 40°, more especially from around 20° to 30°, to the specimen support plane seem quite satisfactory, and though the larger angles give the better results a compromise must be reached between the size of the angle and the concomitant thickness of the receptor. At present the preferred angle is 22°.
  • the receptor has an aperture generally centrally of it and through which the electron beam can pass to illuminate the specimen.
  • This aperture is desirably sufficiently large to permit the scanned electron beam to pass through unhindered even at the lowest magnifications (when it is scanning the largest area of the specimen).
  • An aperture size of around 3 mm diameter is satisfactory for the majority of SEMs.
  • the aperture is lined with a conductive tube that extends slightly beyond the surface of the receptor's scintillator layer; this has the effect that the electron beam stigmation—the beam's essentially round cross-section—is not distorted by small areas of local charging of that layer adjacent the aperture.
  • the tube which can be of almost any conductive internally-reflective material, though polished aluminium is preferred, also shields the preferred slightly asymmetrical form of the receptor from the electron beam, thereby reducing the possibility of astigmatic distortion due to asymmetrical proximity effects.
  • the size and shape of the scintillator-coated receptor substrate can be whatever is appropriate for gathering the emanating electrons; there are, though, certain problems that should be designed for. More specifically, and as can be seen from simple geometry, the angled disposition of the receptor working face coupled with the large size of the receptor relative to the specimen and the spacing between them means that, of the emitted light derived from back-scattered electrons impinging upon the scintillator layer, the quantity entering the light guide from that area of the layer nearest the guide will be significantly larger than that from the area furthest from the guide. Moreover, other factors, such as the light-blocking nature of the receptor's electron-beam aperture and its projecting tube lining, have much the same sort of unbalancing effect.
  • the system has the disadvantage that it will transmit more light, and so seems to be more sensitive, from the side of the receptor that faces the magnifier.
  • This effect is very difficult to overcome completely, but by producing a receptor with an asymmetric face (with the beam aperture located further to the magnifier side), and having a concave working face—either smoothly curved or in two or more flat portions—the light from the far side of the scintillator may be made to have more prominence than light from the near side.
  • a position may be found where reasonably equal collection and transmission is possible from both.
  • the material of the receptor substrate is very preferably a good electrical conductor, by which the charge collected on the supported scintillator layer from the gathered electrons may more easily be drained away to earth (ground).
  • the substrate is, like the guide body, of a metal, for example aluminium.
  • the electron receptor has a scintillator layer on its working face.
  • This scintillator layer may take any suitable form, and may be of any appropriate material. As to form, it is conveniently no more than a thin layer on the receptor substrate, typically from 10 to 100 micrometer thick (the thicker the layer the better the chance that all the electrons are captured, but the greater the likelihood of an light photon emitted deep therein of failing to get back out).
  • material it may, for example, be a phosphor, typically the common P47 phosphor which is highly sensitive and emits light in the region of 440 nm (which closely corresponds to the standard bialkali PMT that is used), but there are a number of other phosphors some of which have better low kV characteristics and some of which have a higher sensitivity at high kVs.
  • the scintillator may employ another type of light-emitting material.
  • single-crystal scintillators of Yttrium Aluminium Garnet (YAG) or Yttrium Aluminium Perovskite (YAP) further extend the capabilities of the invention; these materials are particularly sensitive scintillators.
  • YAG and YAP are also available in powder form, which may be used directly to coat the angled receptor face, and are much less expensive.
  • the detector system of the invention is a considerable improvement on those detectors presently in use. Its sensitivity is much higher than competitive units, and its low kV performance is considerably better than most of its rivals. And due to its high sensitivity and the relatively thin tip, this new detector is ideal for utilisation with field emission SEMs (which are particularly used for the highest magnification applications, and run at very low probe currents; backscattered detection under these conditions has always been difficult, but the new device described will, due to its high sensitivity, help in this critical application).
  • the thin profile of the invention's device also makes it very suitable for use with high pressure SEMs in which, due to the molecules of gas that still remain, backscattered electrons and even the primary electron beam can only travel for a short distance before becoming attenuated or dispersed, so that the specimen must be placed quite close to the electron lens, reducing travelled path length and making the requirement for a thin detector imperative.
  • the detector system of the invention may also be used to considerable advantage in STEM systems in both the SEM and TEM.
  • the scintillator tip is placed beyond the specimen, to receive the electrons that have passed straight through the thin specimen.
  • Bright field images will be seen with the detector directly beneath the specimen, and dark field images when the detector is placed to one side.
  • the detector may be placed a considerable distance to the side of a STEM specimen thereby picking up only those electrons that have been very widely scattered. This information provides further intelligence about the specimen, its composition and its thickness.
  • FIG. 1 shows the main components of a typical scanning electron microscope
  • FIGS. 2A, B show an electron-gathering light guide of the invention in use with a scanning electron microscope
  • FIGS. 3A-C show different forms of electron receptor usable with an electron-gathering light guide of the type shown in FIGS. 2 .
  • the scanning electron microscope shown schematically in FIG. 1 is an instrument that is used to give highly magnified images from a solid specimen. It operates by producing a fine stream or beam of electrons ( 11 ) that come from an electron gun ( 12 ). The beam is guided through various limiting, shaping and directing aperture plates ( 13 , 14 ) and electrostatic and magnetic lenses (from condenser coils 15 , 16 and objective focusing electrode 17 ) so that it forms a very small spot on the solid specimen ( 18 ). The electron beam is scanned from side to side and from top to bottom, in a manner not unlike that of a television screen, using scanning coils ( 19 ); the scanned area of the specimen is extremely small. The whole is contained within a vacuum chamber ( 21 ).
  • FIGS. 2 As the electron beam strikes the specimen, some of the electrons are reflected back (“back-scattered”: see FIGS. 2 ). These electrons contain valuable information about the surface of the specimen from which they have bounced. They may be collected by a suitable detector system, which turns the received signal into a modulated voltage.
  • a suitable detector system which turns the received signal into a modulated voltage.
  • an electron-gathering light guide ( 22 ) mounted on a light magnifier (in this case a photomultiplier tube 23 ) and gathering the back-scattered electrons by an electron receptor ( 24 ) at its tip (the details of this are shown in FIGS. 2 and 3 ).
  • the detector system's photomultiplier's output voltage is amplified and applied to the modulation electrode of a cathode ray tube (CRT), and provides a television-like picture of the scanned area of the sample.
  • CRT cathode ray tube
  • Magnification is controlled by the ratio between the scanned area on the specimen and that on the CRT.
  • the size of the CRT is basically fixed, therefore to increase the magnification the area of the specimen being scanned must be reduced. Conversely, to reduce magnification, it is necessary to increase the area being scanned.
  • the electron beam diameter that is scanned across the specimen must be kept as small as possible—at worst it should be no more than ⁇ fraction (1/100) ⁇ and preferably no more than ⁇ fraction (1/1000) ⁇ part of the width of the picture formed.
  • This fine focusing is done by passing the beam through the several condensing and focusing stages 15 , 16 , 17 .
  • the beam also needs to be kept round and not elliptical or otherwise distorted. This is controlled by astigmatism controls (not shown) which artificially stretch the shape to keep its cross section round.
  • the SEM normally operates with the electron gun at a high negative potential. As noted hereinbefore, this voltage is frequently around 20,000 Volts (20 kV), but operation of most SEMs is possible between 1 kV and 30 kV. Some SEMs operate over a wider range of voltages; operation at the lower kVs is of particular significance in the current invention although the device also performs well at all the usual kVs.
  • the current in the electron beam is very small, and is generally in the range from 1 picoAmpere to 10 nanoAmpere, (10 ⁇ 12 to 10 ⁇ 8 Ampere).
  • SEMs produce the electron beam from various types of electron gun. These include guns producing electrons by thermionic emission from a heated cathode, and guns producing the electrons by field emission where the electrons are extracted from a very fine point with the aid of high extraction voltages. Some SEMs use a combination of both methods.
  • the field emission SEM generally produces less current in the electron beam but the resultant electron beam (or probe size) can be considerably smaller than with thermionic emission.
  • Backscattering is dependent on the elemental composition of the specimen. Generally, for an increase in atomic weight of the specimen the backscattering coefficient will increase. This means that for a specimen containing several phases of different materials the backscattered electrons, if efficiently collected, will show the difference between low and high atomic number areas. This effect is generally monotonic, with the backscattering coefficient increasing almost linearly with atomic number.
  • the high energy electron beam penetrates some small distance into the specimen. The deeper it penetrates, the less chance there is of the electrons being backscattered out again. Those that do penetrate more deeply will loose some of their energy due to multiple collisions, and by the time that they emerge they may not emerge at 180° to the incoming electron beam but will be more widely scattered, emerging at various angles.
  • Backscattered electrons generally travel in a straight line due to their high energies, which makes them quite easy to detect. It is difficult, though, to detect all of them due to the fact that they are usually emitted through a solid angle of around 180°, and to attract such high energy particles into a detector by an electrostatic field would necessitate a voltage of many 1000s of volts, which would cause severe distortions to the primary electron beam, making high resolution operation impossible. Backscattered electrons must therefore be collected at their own energy.
  • the ideal detector is notionally a hemispherical one, fitted above the specimen to wrap around so as to cover a full solid angle of 180°, but this is not really practical.
  • the current in the primary electron beam is commonly between 1 pA and 10 nA; the current in the total backscattered electron emission may be considerably less than that. If a very sensitive amplifier were to be fitted, a signal could be produced at the higher probe currents used, but nothing would be seen from the lower currents. An improved method of detection is therefore necessary.
  • detectors have been produced for the collection of these important backscattered electrons.
  • One, noted hereinbefore, consists of a (retractable) acrylic light-guide finger that sits above the specimen and just below the final lens (at the point where the electrons emerge from the electron optics and scanning system).
  • the detector has in it a small hole, or sometimes a slot, for the electron beam to pass through; on its surface, closest to the specimen, is a layer of a scintillating material, typically a phosphor.
  • a scintillating material typically a phosphor
  • This system gives a reasonably efficient means of sensing these backscattered electrons. It does however have several drawbacks. The most important of these is that, for reasons to do with geometry, absorption and attenuation following multiple reflections, and other factors, the finger, whatever its shape, will show a higher sensitivity in the direction of the PMT. This means that the signal received favours one side of the specimen, and this asymmetry produces a signal that contains some usually unwanted topographic information. This can be a problem when looking for small atomic number differences in the specimen's composition.
  • This type of detector also has another major problem; because it is made of acrylic, it is non-conductive electrically, and the absorbed electrons would ordinarily cause it to become charged until it repelled further electrons. To overcome this the acrylic must be made conductive, usually by the application of a metallic (or similar) coating. But this, too, has its disadvantages; if applied between the scintillator material and the light guide this coating will also restrict the penetration of light into the light guide, while if applied on top of the scintillator material then it acts as a barrier to the lower energy electrons arriving at its surface.
  • this type of finger should be as thick as possible, but this is difficult because in the region between the lens and the specimen space is very limited (typical lens-to-specimen working distances are 12 mm, and for high resolution work this needs to be less). Consequently the detector is made with a thickness of around 6 mm, being a compromise between thickness and efficiency.
  • a third effect of bombarding a specimen with electrons is Cathodoluminescence Emission (certain specimens when excited by an electron beam will produce small quantities of light).
  • the small signals obtained are collected in a similar way to backscattered signals, but without the necessity for a scintillator.
  • a fourth effect is electron absorption. As the electron beam strikes the solid sample some of the electrons penetrate and fail to emerge again at the surface. These are absorbed and pass quickly to ground through the specimen. An image is possible from this signal by passing this small absorbed current through a very sensitive amplifier.
  • the present invention relates to an improved and more efficient form of backscattered electron detector. It is shown schematically in FIGS. 2 .
  • the detector system of the invention is an electron-gathering light guide for attachment to a light magnifier ( 31 ).
  • the guide comprises an elongate light-guiding body ( 22 ) mountable at one end at the magnifier ( 31 ) and carrying (by means not shown) at the other end—the end to be inserted in use into the cone of backscattered electrons (as e) emanating from the specimen—an area-extensive electron receptor (generally 32 in FIG. 2B) disposed so as to have its working face ( 33 ) angled as though to reflect received electrons e along the body to the mounting end, and having on that face a scintillator layer ( 34 ).
  • the receptor substrate is a thin wedge ( 35 ) of polished aluminium, and in the embodiment shown the scintillator layer 34 material is a phosphor deposited directly on it.
  • This thin wedge has a hole ( 36 ) though its centre through which the electron beam 11 passes.
  • the hole is lined with a polished bore aluminium tube ( 37 ) that extends slightly below the lower face 33 where the wedge is coated with the phosphor 34 so that the electron beam stigmation is not distorted by small areas of local charging of the phosphor.
  • the tube 37 also shields the slightly asymmetrical form of the wedge 35 from the electron beam 11 , thereby reducing the possibility of astigmatic distortion due to asymmetrical proximity effects.
  • the wedge 35 is angled such that the PMT has a direct view of its working face 33 , 34 , although at an angle, and is mounted at the end of—effectively “inside”—the light pipe 22 , which is here constructed from four aluminium plates (not shown separately).
  • the guide tapers down to the receptor end, allowing the scintillator's emitted light (as 38 ) to be transmitted either directly to the PMT or by one or more internal reflections.
  • the PMT output is then used to control the image of a video system ( 39 ).
  • the very tip should be as thick as possible for the most efficient transmission of the small light signals; in this particular case, however, the greatly improved sensitivity of the system has permitted some of this efficiency to be sacrificed to keep the tip small (as shown it has a thickness of around 4 mm).
  • the detector system of the invention as so far described still has the disadvantage that it is more sensitive from the side facing the PMT.
  • This effect is very difficult to overcome, but by producing a receptor with a shaped working surface 33 —a concave surface, either curved or in two or more flats—the light from the far side of the scintillator layer may be made to have more prominence than light from the side next to the PMT.
  • FIG. 3 show receptors with a “flat” working face (FIG. 3A) and with shaped faces (FIGS. 3 B,C).

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GB9613728A GB2314926B (en) 1996-07-01 1996-07-01 Detector devices
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JP (1) JP3822911B2 (de)
AT (1) ATE265741T1 (de)
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Cited By (21)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20020171030A1 (en) * 2001-05-18 2002-11-21 Applied Materials, Inc. Phosphor coated waveguide for efficient collection of electron-generated photons
US6545277B1 (en) * 2000-08-15 2003-04-08 Applied Materials, Inc. High efficiency, enhanced detecting in-lens light guide scintillator detector for SEM
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DE102010026169A1 (de) * 2010-07-06 2012-01-12 Carl Zeiss Nts Gmbh Partikelstrahlsystem
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JP2014531129A (ja) * 2011-10-25 2014-11-20 ガタン インコーポレイテッドＧａｔａｎ，Ｉｎｃ． カソードルミネッセンスを収集する光学系を備える一体式の後方散乱電子検出器
EP2503586A3 (de) * 2011-03-22 2014-12-31 JEOL Ltd. Elektronendetektionssystem und damit ausgerüstetes Ladungsteilchenstrahlsystem
CN106981411A (zh) * 2017-05-03 2017-07-25 中国地质大学（北京） 一种聚光系统及其聚光方法
WO2018081404A1 (en) * 2016-10-28 2018-05-03 Arizona Board Of Regents On Behalf Of The University Of Arizona Scintillation detector and associated scintillation detector ring and method
US10236156B2 (en) 2015-03-25 2019-03-19 Hermes Microvision Inc. Apparatus of plural charged-particle beams
US10361062B2 (en) * 2017-02-23 2019-07-23 Jeol Ltd. Scanning electron microscope
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US6545277B1 (en) * 2000-08-15 2003-04-08 Applied Materials, Inc. High efficiency, enhanced detecting in-lens light guide scintillator detector for SEM
US20020171030A1 (en) * 2001-05-18 2002-11-21 Applied Materials, Inc. Phosphor coated waveguide for efficient collection of electron-generated photons
US6775452B2 (en) * 2001-05-18 2004-08-10 Applied Materials, Inc. Phosphor coated waveguide for efficient collection of electron-generated photons
US20030085361A1 (en) * 2001-11-02 2003-05-08 Applied Materials, Inc. Phosphor coated waveguide for the efficient collection of electron-generated photons
US6768836B2 (en) * 2001-11-02 2004-07-27 Applied Materials, Inc. Phosphor coated waveguide for the efficient collection of electron-generated photons
US20050083515A1 (en) * 2003-10-20 2005-04-21 The Regents Of The University Of California Extended surface parallel coating inspection method
US7016030B2 (en) 2003-10-20 2006-03-21 Euv Llc Extended surface parallel coating inspection method
US20060022142A1 (en) * 2004-07-12 2006-02-02 Etp Semra Pty. Ltd. Detector surface for low-energy radiation particles
ES2253118A1 (es) * 2004-11-11 2006-05-16 Universidad De Cadiz Sistema de catadoluminiscencia para microscopio electronico de barrido.
US7560703B1 (en) * 2007-05-21 2009-07-14 Kla-Tencor Corporation Integrated segmented scintillation detector
DE102010026169A1 (de) * 2010-07-06 2012-01-12 Carl Zeiss Nts Gmbh Partikelstrahlsystem
US8598525B2 (en) 2010-07-06 2013-12-03 Carl Zeiss Microscopy Gmbh Particle beam system
DE102010026169B4 (de) * 2010-07-06 2014-09-04 Carl Zeiss Microscopy Gmbh Partikelstrahlsystem
EP2503586A3 (de) * 2011-03-22 2014-12-31 JEOL Ltd. Elektronendetektionssystem und damit ausgerüstetes Ladungsteilchenstrahlsystem
US20130075604A1 (en) * 2011-09-22 2013-03-28 Carl Zeiss Microscopy Ltd. Particle beam system having a hollow light guide
US8648301B2 (en) * 2011-09-22 2014-02-11 Carl Zeiss Microscopy Ltd. Particle beam system having a hollow light guide
JP2014531129A (ja) * 2011-10-25 2014-11-20 ガタン インコーポレイテッドＧａｔａｎ，Ｉｎｃ． カソードルミネッセンスを収集する光学系を備える一体式の後方散乱電子検出器
US20150155133A1 (en) * 2013-03-25 2015-06-04 Hermes Microvision Inc. Charged Particle Beam Apparatus
US10020164B2 (en) * 2013-03-25 2018-07-10 Hermes Microvision Inc. Charged particle beam apparatus
US20150083912A1 (en) * 2013-03-25 2015-03-26 Hermes Microvision Inc. Charged Particle Beam Apparatus
US20140291510A1 (en) * 2013-03-25 2014-10-02 Hermes-Microvision, Inc. Charged Particle Beam Apparatus
US9190241B2 (en) * 2013-03-25 2015-11-17 Hermes-Microvision, Inc. Charged particle beam apparatus
US10586681B2 (en) 2013-03-25 2020-03-10 Asml Netherlands B.V. Charged particle beam apparatus
US9362087B2 (en) * 2013-03-25 2016-06-07 Hermes Microvision, Inc. Charged particle beam apparatus
US9734987B2 (en) 2013-04-27 2017-08-15 Kla-Tencor Corporation Method and system for adaptively scanning a sample during electron beam inspection
US9257260B2 (en) * 2013-04-27 2016-02-09 Kla-Tencor Corporation Method and system for adaptively scanning a sample during electron beam inspection
US20140319342A1 (en) * 2013-04-27 2014-10-30 Kla-Tencor Corporation Method and System for Adaptively Scanning a Sample During Electron Beam Inspection
US10236156B2 (en) 2015-03-25 2019-03-19 Hermes Microvision Inc. Apparatus of plural charged-particle beams
US11217423B2 (en) 2015-03-25 2022-01-04 Asml Netherlands B.V. Apparatus of plural charged-particle beams
US11282671B2 (en) * 2016-07-28 2022-03-22 Hitachi High-Tech Corporation Charged-particle beam apparatus
WO2018081404A1 (en) * 2016-10-28 2018-05-03 Arizona Board Of Regents On Behalf Of The University Of Arizona Scintillation detector and associated scintillation detector ring and method
US11385362B2 (en) 2016-10-28 2022-07-12 Arizona Board Of Regents On Behalf Of The University Of Arizona Scintillation detector and associated scintillation detector ring and method
US10361062B2 (en) * 2017-02-23 2019-07-23 Jeol Ltd. Scanning electron microscope
CN106981411B (zh) * 2017-05-03 2018-02-13 中国地质大学（北京） 一种聚光系统及其聚光方法
CN106981411A (zh) * 2017-05-03 2017-07-25 中国地质大学（北京） 一种聚光系统及其聚光方法
US20210183614A1 (en) * 2018-09-21 2021-06-17 Hitachi High-Tech Corporation Charged particle beam apparatus
US11515120B2 (en) * 2018-09-21 2022-11-29 Hitachi High-Tech Corporation Charged particle beam apparatus
US20230030651A1 (en) * 2018-09-21 2023-02-02 Hitachi High-Tech Corporation Charged particle beam apparatus
US11694873B2 (en) * 2018-09-21 2023-07-04 Hitachi High-Tech Corporation Charged particle beam apparatus
US11239048B2 (en) * 2020-03-09 2022-02-01 Kla Corporation Arrayed column detector
CN113675061A (zh) * 2020-05-13 2021-11-19 聚束科技（北京）有限公司 一种扫描电子显微镜

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EP0914669A1 (de) 1999-05-12
AU714501B2 (en) 2000-01-06
JP3822911B2 (ja) 2006-09-20
GB9613728D0 (en) 1996-09-04
AU3269697A (en) 1998-01-21
WO1998000853A1 (en) 1998-01-08
DE69728885T2 (de) 2005-04-07
JP2000513487A (ja) 2000-10-10

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